Cristina Manuel, Laura Tolos
We analyze how recent computations of the shear viscosity $\eta$ in the core of superfluid neutron stars affect the r-mode instability window. We take into account the contribution of superfluid phonons to the viscosity, both in their hydrodynamical and ballistic regime. Moreover, we also consider the recent computation of $\eta$ arising from the collisions of electrons with electrons and protons dominated by transverse plasmon exchange. We also discuss how the interactions among superfluid phonons and electrons might contribute to the shear viscosity, but argue that these interactions will be not be relevant for the study of r-mode damping. At very low temperatures, $T < 10^8$ K, the electron contribution to $\eta$ dominates, as then phonons are in a ballistic regime, and they mainly interact with the crust of the star. At higher temperatures the superfluid phonon contribution to $\eta$ is purely hydrodynamic and starts to dominate the process of r-mode damping. While our results for the instability window are preliminary, as other dissipative processes should be taken into account as well, they differ substantially from previous evaluations of the r-mode damping due to the shear viscosity in superfluid neutron stars.
View original:
http://arxiv.org/abs/1212.2075
No comments:
Post a Comment